Therapeutic percussors and vibrators are known and used to stimulate expectoration of mucous from the lungs. It has been found that by applying undulating or vibratory action to the area of the body adjacent to the thoracic cavity, postural draining or coughing up of sputum is induced thereby reducing the amount of mucous that lines the inner walls of the alveoli.
Various pneumatic and mechanical types of percussors are known in the art. For example, U.S. Pat. No. 4,580,107 to Strom et al. discloses a pneumatic percussor for stimulating the expectoration of mucous. Similarly, U.S. Pat. No. 3,955,563 to Maione discloses a pneumatic percussor useful in the therapeutic treatment of cystic fibrosis and other lung disorders.
Low air loss patient support structures or beds are also known in the medical field. The structures essentially consist of a plurality of inflatable sacs disposed on a frame structure. The patient""s weight is uniformly distributed over the supporting surface area of the inflatable sacs. Low air loss beds are known in the art claiming therapeutic value in pulmonary and circulatory care. Low air loss beds are also considered helpful in preventing and treating pressure sores. Exemplary low air loss beds relating to wound care management and prevention include the Flexicair and Restcue beds provided by Support Systems International, Inc.
Alternating pressure low air loss beds are also known in the art. For example, U.S. Pat. No. 5,044,029 to Vrzalik discloses a low air loss bed having first and second sets of air bags alternating positioned in an interdigitated fashion. Valves and circuitry are provided for alternately changing the pressure in each of the sets of bags to selectable maximum and minimum pressure above and below a predetermined baseline pressure in repetitive and cyclical fashion. Low air loss beds are also known for turning or rotating a patient from side to side in a cyclic fashion, for instance the Biodyne bed by Kinetic Concepts, Inc.
Support Systems International, Inc. markets the Restcue bed having the ability to operate in a first static mode, a second pulsation mode, and a third patient turning mode. The Restcue Bed employs a uniquely designed inflatable sac, as disclosed in U.S. Pat. No. 4,949,414, to operate in any one of the three modes.
Until now, the vibratory therapeutic treatment of lung disorders, such as cystic fibrosis, has not been combined with the benefits of low air loss technology. Previously, a patient restricted to a low air loss bed, such as the Restcue bed, who also required percussive chest therapy to induce mucociliary clearance required an external mechanical or pneumatic type vibrator, such as the Strom device. This device would be applied directly to the patient""s upper torso to loosen the mucous.
It is also known in the art to provide vibratory pads or similar supports upon which a patient can lie or sit. U.S. Pat. No. 4,753,225 to Vogel, for example, discloses an oscillator plate on which a body can sit, lie, or stand. The oscillator plate is made to oscillate by sound waves. U.S. Pat. No. 4,583,255 to Mogaki et al. discloses a massage mat having a plurality of juxtaposed air chambers. A repeated rhythmic wave motion is induced over the entire surface of the mat or in a local surface by repeating a succession of feeding and discharging of compressed air into and from the air chambers. U.S. Pat. No. 4,551,874 to Matsumura et al. discloses a similar pneumatic massage mat.
The patient care industry has become sensitive to the rising cost of health care in this country. Sophisticated therapy devices such as the low air loss beds described, although very effective in their method, can amount to significant expense if the patient requires sustained use of the bed. The more versatile these beds can be made, the more the expense of the bed can be spread among a wider patient basis. For example, a low air loss bed also incorporating a vibratory therapy mode of operation could be used to treat a first patient suffering from pressure ulcers and a second patient suffering from a lung disorder. The present invention provides such a unique and versatile patient support system and marks a significant advance in the art of low air loss specialty hospital beds.
In accordance with the present invention, as embodied and broadly described herein, the vibratory patient support system of the present invention preferably includes a rigid support frame that carries the other components of the system. The frame is mounted on castors for ease of movement and preferably has a plurality of articulatable sections that can be lifted by conventional hydraulic lifting mechanisms and articulated by conventional articulation devices.
In accordance with the present invention, a plurality of inflatable sacs are supported upon the rigid support frame. The sacs are preferably disposed transversely across the patient support system but, may be disposed lengthwise thereto. Each sac may comprise a single internal chamber but preferably has four uniquely defined chambers, including two opposite end chambers and two intermediate chambers. The inflatable sacs of the present invention are uniquely designed so that the patient support system can operate in any one of three operational modes with at least one portion or region of the inflatable sacs having a vibratory capability.
The present invention further comprises means for pressurizing and maintaining the inflatable sacs at a predetermined pressure. The predetermined pressure may be a patient height and weight specific profile which can be varied or adjusted accordingly. Vibrating means are further provided separate from the pressurizing and maintaining means. The vibrating means are for vibrating at least a portion of the patient support surface of the system in a frequency range of, for example, 1 Hz to 50 Hz. The frequency range may be as high as desired. The vibrating means are separate from the pressurizing means in that the inflatable sacs can be maintained at the predetermined pressure profile and operate in any mode while a portion of the patient support surface is simultaneously vibrated at a predetermined frequency within the frequency range. Means for variably controlling the vibrating means are also provided which may include, for example, varying the frequency and magnitude or amplitude of vibrations imparted to the patient support surface.
In another preferred embodiment of the invention, the support frame is articulatable in sections with at least one of the sections corresponding to the general area of the patient""s chest. In this embodiment, the vibrating means are disposed within at least one of the inflatable sacs located in the section corresponding to the patient""s chest. In this manner, the vibrating forces are localized so as to be applied to the general area of the upper torso of a patient, thereby providing respiratory therapy.
The means for pressurizing and maintaining the inflatable sacs at a predetermined pressure preferably comprises means for pressurizing the inflatable sacs in a first constant pressure mode so that the inflatable sacs are maintained at a relatively constant predetermined pressure whereby a patient resting upon the patient support surface is supported at a predetermined relatively static pressure. Preferably, means are further provided for pressurizing the inflatable sacs in a second pulsation mode whereby at least two alternate sets of the inflatable sacs are alternately inflated and deflated so as to provide alternating pressure point relief to a patient resting upon the support surface. Means are also preferably provided for pressurizing the inflatable sacs in a third turning mode whereby generally disposed portions of each inflatable sac are alternately inflated and deflated so that a patient resting upon the sacs can be automatically tilted from side to side. In this preferred embodiment of the present invention, the patient support system is switchable from any one of said modes of operation to any other mode of operation with the vibrating means being independently actuable and controllable from any of the modes of operation.
In another preferred embodiment of the invention, the vibrating means may comprise a pneumatic vibrating system. This pneumatic vibrating system may include a source of pressurizing air and at least one inflatable cell or pod disposed within at least one of the inflatable sacs generally near the top thereof. The inflatable cell may be supported within the sac by flexible internal slings or like structure. The inflatable cell may also form an integral part of the inflatable sac. For example, the top of the inflatable cell may also be the top of the inflatable sac. The inflatable cell is in pneumatic communication with the source of pressurized air so that pressurized air can be directed into the inflatable cell causing the cell to expand. Controllable valve means are preferably provided between the source of pressurized air and the inflatable cell. The valve means operate to alternately supply pressurized air from the pressurized air source to the cell and to vent the pressurized air from the cell at a predetermined frequency. In this manner, the inflatable cell pneumatically vibrates, in other words, contracts and expands, just below the upper surface of the inflatable sac and thereby imparts vibrational forces to the patient support surface. A control circuit is also provided for controlling the operational frequency of the controllable valve means.
In another preferred embodiment of the invention, a plurality of the inflatable cells may be provided for imparting the vibrational forces to the patient support surface. The plurality of cells may be disposed within at least two of the inflatable sacs. In a preferred embodiment, the inflatable cells are disposed within those sacs corresponding to the general area of a patient""s chest or upper torso. In still another preferred embodiment, more than one inflatable cell may disposed within any given inflatable sac.
Preferably, the pneumatic vibrating system is in operative pneumatic communication with the means for pressurizing and maintaining the sacs at a predetermined pressure. In this embodiment, the pneumatic vibrating system and the pressurizing means share a common source of pressurized air. In a preferred embodiment, this source of pressurized air comprises a variable speed blower.
In another preferred embodiment of the pneumatic vibrating system according to the present invention, the inflatable cell may also comprise a diaphragm generally at the top of the cell just below the upper surface of the inflatable sac. The diaphragm acts to snap against the upper surface of the inflatable sac upon the inflatable cell being pressurized. Once the inflatable cell is vented, the diaphragm retracts from the upper surface to again snap against the surface once the cell is subsequently inflated, and so forth.
The present invention encompasses any suitable vibrating means or system which cooperates with the inflatable sacs to provide vibrational therapy in at least one section of the sacs. Although the pneumatic vibrating system is a preferred embodiment, the present invention encompasses suitable mechanical vibrating devices as well. For example, mechanical vibrating pistons or like devices may be disposed internally or externally to the inflatable sacs to cause the patient support surface to vibrate at a desired frequency and magnitude. Such embodiments are encompassed by the spirit of the present invention.
In further accordance with the purpose of the present invention, a low air loss patient support system of the type having a plurality of alternately disposed low air loss sacs supported on a bed frame is provided, the patient support system includes means for pressurizing the sacs and maintaining the sacs at a predetermined pressure which may be a height and weight specific pressure profile for a particular patient. The upper surfaces of the low air loss sacs form a patient support surface. The low air loss patient support system of this embodiment further comprises means internal to at least one of the low air loss sacs for imparting vibrational forces to at least a portion of the patient support surface while the sacs are simultaneously maintained at the predetermined pressure profile.
Preferably, the low air loss patient support system is divided into sections. Control means are provided for maintaining the sacs within each section at a particular predetermined pressure by computing and maintaining a height and weight specific pressure profile for each section. The vibrational forces imparting means is independently actuable and controllable relative to the control means for maintaining the sacs at a predetermined pressure. In this embodiment, the low air loss patient support system can function regardless of whether the vibrational system is actuated. On the other hand, actuation of the vibrational force system in no way degrades or effects the low air loss aspect of the patient support system.
In yet another preferred embodiment of the low air loss patient support system according to the invention, the patient support system can operate in any one of a plurality of operational modes including a first constant pressure mode, a second pulsating mode, and a third turning mode, with the vibrational forces imparting means being independently actuable and controllable in any one of the operational modes.
In further accordance with the purposes of the present invention, a vibratory therapy device is provided for the treatment of respiratory ailments. The vibratory therapy device comprises an inflatable patient support surface and means for maintaining the inflatable patient support surface at a predetermined pressure profile. The maintaining means controls the internal relative pressure of the inflatable patient support surface. Means are further provided independent of the maintaining means for simultaneously imparting therapeutic vibrational forces to at least a portion of the patient support surface while the support surface is separately maintained at the predetermined pressure profile.
In still further accordance with the purposes of the present invention, a vibratable inflatable sac is provided for use with an inflatable patient support system, whereby a plurality of the inflatable sacs form a patient support surface. Each inflatable sac preferably comprises at least one internal chamber. Means are provided for connecting the internal chamber to a source of pressurized air so that the inflatable sac can be pressurized and maintained at a predetermined pressure. Pneumatic vibrating means are carried internal to the inflatable sac. The vibrating means are disposed within the internal chamber generally near the top thereof just below the upper surface of the inflatable sac. Means are further provided for connecting the vibrating means to a source of pressurized air so that the vibrating means can be alternately pressurized and vented at a predetermined frequency thereby imparting a therapeutic vibrational force to the top of the inflatable sac. In a preferred embodiment, the pneumatic vibrating means are connectable to a pressurized air source common to the means for pressurizing the internal chambers of the air sac. Preferably, the inflatable air sac is a low air loss sac.
In accordance with the present invention, a plurality of elongated inflatable sacs are disposed transversely across the patient support system. Each sac may have one internal chamber but preferably has four separately defined chambers, including two opposite end chambers and two intermediate chambers. Each sac is uniquely designed so as to operate in any one of three operational modes.
A separate sac entrance opening is defined through the bottom of each end chamber. Each intermediate chamber preferably is shaped as a right angle pentahedron and has a diagonal wall that faces the center of the sac, and a base wall that preferably forms a common wall with the adjacent end chambers"" vertically disposed internal side wall. Preferably, a single web forms the diagonal wall of both intermediate chambers. Because of the shape of the intermediate chambers, one is disposed predominately to the left side of the patient support, and the other is disposed predominately to the right side of the patient support. A restrictive flow passage is defined through the common wall between each end chamber and each adjacent intermediate chamber. Preferably, the restrictive flow passage includes a hole defined by a grommet having an opening therethrough and mounted in a web that forms both the base wall of an intermediate chamber and the vertically disposed internal side wall of the end chamber adjacent the intermediate chamber. The grommet is sized to ensure that the end chambers have filling priority over the intermediate chambers. Especially when the patient is being supported atop the section of the sac which includes the intermediate chambers, the end chambers fill with air before the intermediate chambers and collapse for want of air after the intermediate chambers.
In still further accordance with the present invention, means are provided for supplying air to each sac and the vibrating system. The means for supplying air to each sac preferably includes a blower electrically powered by a motor so that the blower can supply pressurized air to the sacs and inflatable cells.
The means for supplying air to each sac further preferably includes a support member carried by the frame. The support member preferably is rigid to provide a rigid carrier on which to dispose the sacs and may comprise a plurality of separate non-integral sections so that a one-to-one correspondence exists between each support member section and each articulatable section of the frame. Each section of the rigid support member preferably comprises a modular support member that defines a multi-layered plate which has an upper layer, a lower layer and a middle layer between the other two. The three-layered plate has a top to surface, a bottom surface, two opposed ends, and two opposed side edges. A plurality of inlet openings are defined through at least one of the side edges. In appropriate embodiments, a plurality of exit openings are defined in the opposite side edge. For example, the plate at each end of the patient support only has inlet openings defined through one of the side edges. A plurality of air sac supply openings are defined through the plate from the top surface and preferably extend completely through the three layers of the plate. In at least one of the plates, preferably the seat plate, a plurality of pressure control valve openings are defined through the bottom surface of the plate. A plurality of channels preferably are defined and enclosed between the top surface and the bottom surface of the plate and connect the various inlet openings, outlet openings, air sac supply openings, and pressure control valve openings to achieve the desired configuration of air supply to each of the sacs disposed atop the top surface of the plate.
In yet further accordance with the present invention, the means for supplying gas to the sacs and inflatable cells also preferably includes a hand-detachable airtight connection comprising one component secured to the air sac and a second component secured to the modular support member. The force required to connect and disconnect these components is low enough to permit these operations to be accomplished manually by hospital staff without difficulty. Both components preferably are formed of a resilient plastic material. One of the components comprises an elongated female connection fitting that has an exterior configured to airtightly engage an air sac supply opening defined through the modular support member. A locking nut screws onto one end of the fitting, which extends through the bottom plate, and secures the fitting to the air sac supply opening of the modular support member. The fitting preferably has an axially disposed cylindrical coupling opening with a fitting groove defined completely around the interior thereof and near one end of the cylindrical coupling opening. A resiliently deformable flexible O-ring is held within the fitting groove. A channel opening is defined through the coupling cylinder in a direction normal to the axis of the coupling cylinder and is disposed to be aligned with the support member channel that connects to the air sac supply opening which engages the fitting. A spring-loaded poppet is disposed in the cylindrical coupling opening and is biased to seal the coupling opening.
The other component of the connection includes an elongated coupling that is secured at one end to the air entrance opening of the sac or inflatable cell and extends outwardly therefrom. The coupling has an axially defined opening that permits air to pass through it and into the sac or cell. The exterior of the coupling is configured to be received within the interior of the connection fitting""s cylindrical coupling opening. Insertion of the coupling into the interior of the fitting depresses the poppet sufficiently to connect the channel opening with the axially defined opening of the coupling. The coupling""s exterior surface defines a groove that is configured to receive and seal around the deformable O-ring of the connection fitting therein when the coupling is inserted into the connection fitting. The O-ring seals and provides a mechanical locking force that holds the coupling in airtight engagement with the fitting. The coupling preferably is secured to extend from the air entrance opening of the air sac with the aid of a grommet and a retaining ring. The grommet preferably is heat sealed to the fabric of the air sac on the interior surface of the air sac around the air entrance opening. The coupling extends through the grommet and the air entrance opening. A pull tab is fitted over the coupling and rests against the exterior surface of the air sac. A retaining ring is passed over the coupling and mechanically locks against the coupling in air-tight engagement with the air sac. The pull tab can be grasped by the hand of a person who desires to disconnect the coupling from the fitting. In this way, the material of the air sac need not be pulled during disconnection of the coupling from the fitting. This prevents tearing of the air sac near the air entrance opening during the disconnection of the coupling from the fitting.
The coupling between the inflatable cells of the vibrating system and the pressurized air source also preferably includes a hand detachable airtight connection, which may be similar to the connection just described or a like connection.
In still further accordance with the present invention, the means for supplying air to each of the sacs further preferably includes a modular manifold for distributing air from the blower to the sacs and the inflatable cells. The modular manifold preferably provides means for mounting at least two pressure control valves thereon and for connecting these valves to a source of pressurized air and to an electric power source. As embodied herein, the modular manifold preferably includes a log manifold that has an elongated body defining a hollow chamber within same. A supply hose is connected to the main body and carries pressurized air from the blower to the hollow chamber of the main body. End walls are defined at the narrow ends of the main body and contain a conventional pressure check valve therein to permit technicians to measure the pressure inside the hollow chamber of the main body.
One section of the main body defines a mounting wall on which a plurality of pressure control valves and vibrational system valves can be mounted by inserting their valve stems into one of a plurality of ports defined through the mounting wall and spaced sufficiently apart from one another to permit side-by-side mounting of the valves. Each port has a bushing mounted therein to engage one or more O-rings on the valve stem of each valve. This renders each valve easily insertable and removable from the log manifold. The log manifold further preferably includes a circuit board that preferably is mounted to the exterior of the main body adjacent the mounting wall and includes electronic circuitry for transmitting electronic signals between a microprocessor and the valves mounted on the log manifold. A plurality of electrical connection fittings are disposed on the circuit board, and each fitting is positioned in convenient registry with one of the ports defined through the mounting wall. These electrical connection fittings are provided to receive an electrical connector of each pressure control valve, one or more fuses are provided on the circuit board to protect it and the components attached to it. Preferably, the fuses are mounted on the exterior of the log manifold to provide technicians with relatively unobstructed access to them to facilitate troubleshooting and fuse replacement.
In further accordance with the present invention, means are provided for maintaining a predetermined pressure in the sacs separate and independent of the vibrating means. As embodied herein, the means for maintaining a predetermined pressure in the sacs preferably includes a pressure control valve. In a preferred embodiment, a plurality of pressure control valves are provided, and each pressure control valve controls the pressure to more than one sac or more than one chamber of a sac. As embodied herein, each pressure control valve includes a housing having an inlet defined through one end and an outlet defined through an opposite end. An elongated valve passage is defined within the housing and preferably is disposed in axial alignment with the inlet. The longitudinal axis of the passage preferably is disposed perpendicularly with respect to the axis of the valve outlet which is connected to the passage. The housing further defines a chamber disposed between the inlet and a first end of the valve passage and preferably is cylindrical with the axis of the cylinder disposed perpendicularly with respect to the axis of the passage. The valve further preferably includes a piston that is disposed within the chamber and preferably rotatably displaceable therein to vary the degree of communication through the chamber that is permitted between the valve inlet and the valve passage. The valve further includes an electric motor that is mounted outside the housing and near the chamber. The motor is connected to the piston via a connecting shaft that has one end non-rotatably secured to the rotatable shaft of the motor and an opposite end non-rotatably connected to the piston, which also is cylindrical in shape. The piston has a slot extending radially into the center of the piston so that depending upon the position of this slot relative to the inlet and the passage, more or less air flow is permitted to pass through the holes between the inlet and the passage. Accordingly, the position of the piston within the chamber determines the degree of communication that is permitted through the chamber and thus the degree of communication permitted between the valve passage and the valve inlet. This degree of communication effectively regulates the pressure of the air flowing through the valve. Preferably, the piston slot is configured so as to provide a linear change in pressure as the piston is rotated.
The pressure control valve further preferably includes a pressure transducer that communicates with the valve passage to sense the pressure therein. The pressure transducer converts the pressure sensed in the valve passage into an electrical signal that is transmitted to an electronic circuit mounted on a circuit card of the valve. The circuit card receives the electrical signal transmitted from the transducer corresponding to the pressure being sensed in the valve passage. The circuit card has a comparator circuit that compares the signal from the transducer to a reference voltage signal received from a microprocessor via the circuit board of the log manifold. The valve circuit controls the valve motor according to the result of the comparison of these signals received from the microprocessor and transducer to open or close the valve to increase or decrease the pressure. The control valve has an electrical lead that is connected to the valve circuit card and terminates in a plug that can be connected to the electrical connection fitting on the log manifold.
A dump outlet hole is defined through the valve housing in the vicinity of the valve chamber. A dump passage is also defined through the valve piston and is configured to connect the dump hole to the valve passage upon displacement of the piston such that the dump hole becomes aligned with the dump passage of the piston. When the dump hole becomes aligned with the dump passage of the piston, the valve inlet becomes completely blocked off from any communication with the valve passage. Upon suitable operator control of the microprocessor, the dump hole becomes connected to the valve passage via the dump passage of the piston to permit the escape of air from the sacs to the atmosphere in a rapid deflation cycle.
A conventional pressure check valve is mounted in a manual pressure check opening defined through the housing of the pressure control valve. This permits the pressure inside the pressure control valve to be manually checked for purposes of calibrating the pressure transducer for example.
The means for maintaining a predetermined pressure preferably further includes a programmable microprocessor, which preferably is preprogrammed to operate the pressure control valves and the blower to pressurize the sacs at particular reference pressures. The microprocessor calculates each sac reference pressure according to the height and weight of the patient, and the portion of the patient being supported by the sacs connected to the respective pressure control valve. For example, the sacs supporting the head and chest of the patient may require a different pressure than the sacs supporting the feet of the patient. The pressures also differ depending upon whether the patient is lying on his/her side or back. A control panel is provided to enable the operator to provide this information to the microprocessor, which is programmed to calculate a separate reference pressure for each mode of operation of the patient support for each pressure control valve. The microprocessor uses an algorithm to perform the calculation of the sac reference pressure, and this algorithm has constants which change according to the elevation of the patient, the section of the patient being supported, and whether the patient is lying on the patient""s side or the patient""s back.
The output of the blower preferably is controlled by a blower control circuit which receives a control voltage signal from the microprocessor. A pressure transducer measures the pressure preferably at the outlet of the blower, and this measured pressure is supplied to the microprocessor which stores it in one of its memories. This memory is not continuously updated, but rather is updated once every predetermined interval of time in order to filter out brief transient pressure changes in the measured pressure so that such transients do not affect control over the blower. The microprocessor uses the highest pressure in the sacs to calculate a reference pressure for the blower higher than the highest sac pressure. The microprocessor is preprogrammed to compare the reference pressure with the measured pressure. If this comparison has a discrepancy greater than a predetermined discrepancy of about one inch of standard water, then the microprocessor changes the control voltage provided to the blower control circuit so as to reduce this discrepancy.
The sacs of the support system are preferably divided into separate body zones corresponding to a different portion of the patient""s body requiring a different level of pressure to support same. Each body zone is controlled by two pressure control valves in one operational mode, one for the chambers on one side of the sacs and one for the chambers on the other side of the sacs. In another operational mode, the two pressure control valves are connected so that each pressure control valve controls the pressurization of the chambers in both sides of every alternate sac in the body zone. The microprocessor is preprogrammed to calculate an optimum reference pressure for supporting the patient in each body zone. This reference pressure is determined at the valve passage where the pressure transducer of each pressure control valve is sensing the pressure. This reference pressure is calculated based upon the height and weight of the patient. Once this reference pressure has been calculated for the particular patient and for the particular mode of operation of the patient support system, for example, turning mode at a particular attitude, pulsation mode at a particular level of depressurization, standard operating mode, etc., the microprocessor signals the circuit board which transmits this signal to the circuit card of the pressure control valve. The circuit card of the valve compares the pressure being measured by the transducer in each valve passage with the reference pressure which the microprocessor has calculated for the particular conditions of operation. Depending upon whether the measured pressure is greater than or lower than the calculated reference pressure, the circuit card signals the valve""s motor to open or close the valve to increase or decrease the pressure to arrive at the target reference pressure. The circuit card continuously monitors this comparison and controls the valves accordingly.
The microprocessor preferably has parallel processing capability and is connected electrically to the circuit board of the log manifold via a ribbon cable electrical connector. The parallel processing capability of the microprocessor enables it to monitor and control all of the pressure control valves simultaneously, as opposed to serially. This increases the responsiveness of the pressure controls to patient movements in the support system.
In still further accordance with the present invention, there is provided means for switching between different modes of pressurizing the sacs. As embodied herein, the mode switching means preferably includes at least one flow diverter valve. The number of flow diverter valves depends upon the number of different pressure zones desired for the patent support system. Each pressure zone, also known as a body zone, includes one or more sacs or sac chambers which are to be maintained with the same pressure characteristics. In some instances for example, it is desired to have opposite sides of the sac maintained at different pressures. In other instances for example, it becomes desirable to have the pressure in every other sac alternately increasing together for a predetermined time interval and then decreasing together for a predetermined time interval.
Each flow diverter valve preferably is mounted within a modular support member and includes a first flow pathway and a second flow pathway. The ends of each flow pathway are configured to connect with the ends of two separate pairs of channels defined in the modular support member. The flow pathways are mounted on a rotating-disk that can be rotated to change the channels to which the ends of the two flow pathways are connected. This changes the flow configuration of the path leading from the blower to the individual sacs and sac chambers. At one position of the rotating disk, all of the chambers on one side of the sacs of a body zone are connected to the blower via one pressure control valve and all of the other sides of the sacs in the body zone are connected to the blower via a second pressure control valve. In a second position of the rotating disk, every alternate sac in the body zone has its chambers on both sides connected to one pressure control valve, and every other alternate sac in the body zone has both of its chambers connected to the blower via a second pressure control valve. Switching between the two positions of the rotating disk changes the flow configuration from the blower to the individual chambers of the sacs. This enables the present invention to be operated in two distinctly different modes of operation with a minimum number of valves and connecting pathways.
The phrase xe2x80x9cpressure profilexe2x80x9d is used herein to describe the range of pressures in the sacs of the patient support system at any given support condition. The pressure in the sacs in one body zone of the support system likely will be different from the pressure in the sacs of another body zone because the different weight of different portions of the patient""s body imposes a corresponding different support requirement for each particular body zone. If the individual pressures in the sacs of all of the body zones were to be represented on a bar graph as a function of the linear position of the sacs along the length of the patient support, a line connecting the tops of the bars in the graph would depict a certain profile. Hence, the use of the term xe2x80x9cpressure profilexe2x80x9d to describe the pressure conditions in all of the sacs at a given moment in time, either when the pressures are changing or in a steady state condition.
In accordance with one of the methods of the present invention made possible by the support system of the present invention, the patient can be automatically tilted from side-to-side in a predetermined sequence of time intervals. The method of turning or tilting the patient includes the step of configuring the flow pathway from the blower to the sacs in each body zone such that the two chambers in one side of each of the sacs are controlled by one pressure control valve, and the two chambers in the other side of each of the sacs are controlled by another pressure control valve.
The step of separately controlling the air pressure that is supplied to each side of each of the sacs in each body zone preferably is accomplished by correctly configuring the flow diverter valve. The next step in tilting or turning the patient involves lowering the pressure in the side of the sacs to which the patient is to be tilted. The pressure must be lowered from a first pressure profile, which previously was established to support the patient in a horizontal position, to a predetermined second pressure profile which depends upon the height and weight of the patient and the angle to which the patient is to be tilted. The next step in the method of tilting or turning the patient requires raising the pressure in the side of the sacs that is opposite the side to which the patient is being tilted. This requires raising the pressure in the non-tilted side of each of the sacs to a predetermined third pressure profile. This raised pressure compensates for the lower pressure profile in the tilted side of the sacs. Thus, the overall pressure being supplied to support the patient remains sufficient to support the patient in the tilted position.
Preferably the steps of lowering the pressure in one side of the sacs occurs in conjunction with and at the same time as the step of raising the pressure in the other sides of the sacs. The changes in pressure are effected under the control of the microprocessor which calculates the desired reference pressure for the tilted condition based upon the height and weight of the patient and transmits a corresponding reference voltage signal to the circuit card of the pressure control valve which closes the valve opening until the desired pressure has been attained, as signaled by the pressure transducer monitoring each pressure control valve. The microprocessor can be programmed to maintain the patient in the tilted position for a predetermined length of time. At the end of this time, the microprocessor can be programmed to return the patient gradually to the horizontal position by reversing the procedure used to tilt the patient. In other words, the pressure is increased to the side of the sacs to which the patient has been tilted, and decreased for the other side of the sacs until both sides of the sacs attain the first predetermined pressure profile.
The method of tilting or turning the patient also includes the step of restraining the patient from slipping off of the sacs while in the tilted condition. This is accomplished by the unique construction of the multi-chambered sacs and the manner in which the sacs are depressurized and deflated. The grommet which defines the hole connecting each intermediate chamber with each end chamber plays a particularly important role in the ability of each sac to restrain the patient from slipping off of the sac during tilting. As the pressure control valve controlling the side of the sac to which the patient is to be tilted begins to close, it reduces the pressure being supplied to this side of these sacs. Thus, the pressure being supplied to the end chamber and the intermediate chamber connected thereto via the flow restriction passage defined through the grommet are both being reduced in pressure. Recall that the microprocessor presets the pressure in the sac depending upon the height and weight of the patient. Once the pressure is reduced from that preset pressure, the weight of the patient above the intermediate chamber begins to squeeze the air from the intermediate chamber through the grommet and into the end chamber. This reduction in pressure results in the deflation of the intermediate chamber while the end chamber continues to remain fully inflated, though at the same reduced pressure as the connected intermediate chamber. Since the end chamber remains inflated, it remains vertically disposed at the end of the sac, and as such the inflated end chamber acts as a constraint that prevents the patient from rolling past the end chamber and slipping off the sacs of the patient support.
In further accordance with the present invention, a method is provided for using the patient support system of the invention to provide pressure point relief between the sacs and the patient by operating the patient support in a pulsation mode of operation. As embodied herein, the method for providing pressure point relief preferably includes the step of configuring the patient support system so that in each body zone, every alternate sac is pressurized via one pressure control valve and every other alternate sac is pressurized via a second pressure control valve. This step preferably is accomplished by configuring the flow diverter valve to reconfigure the flow path to connect every other adjacent sac in each zone to a separate pressure control valve. The next step of the method includes supplying air pressure at a first pressure profile to the sacs connected to one of the pressure control valves and supplying the sacs connected to the other pressure control valve at the same first pressure profile.
The method for pulsating the pressure in the sacs further includes the step of decreasing the pressure being supplied to the sacs through one of the pressure control valves during a first interval of time. The pressure is decreased until a predetermined second pressure profile is being provided to the sacs in this first group, which includes every alternate sac.
The method of pulsating the pressure in the sacs also includes the step of increasing the pressure being supplied to the sacs through the other of the pressure control valves during the same first interval of time. The pressure is increased until a predetermined third pressure profile is being provided to the sacs in this second group, which includes the other set of alternating sacs. Preferably, the third pressure profile is determined so that the average of the second and third pressure profiles equals the first pressure profile.
The method for pulsating the pressure in the sacs next includes the step of maintaining the first group of alternating sacs at the second pressure profile while maintaining the sacs in the second group of alternating sacs at the third pressure profile. This maintenance step occurs over a second interval of time.
The method for pulsating the pressure in the sacs next includes the step of increasing the pressure in the first group of alternating sacs until the third pressure profile is attained while decreasing the pressure being supplied to the sacs in the second group of alternating sacs until the second pressure profile is attained for the second group of alternating sacs. Thus, the pressure profiles of the two groups of alternating sacs are reversed during a third interval of time.
Finally, the method of pulsating the pressure in the sacs includes the step of maintaining the sacs in the first group of alternating sacs at the third pressure profile while maintaining the sacs in the second group of alternating sacs at the second pressure profile. This maintenance step of the method occurs during a fourth interval of time. This completes one full cycle of pulsation, and this can be repeated as long as the repetition is deemed to be therapeutic. Preferably, the time intervals are equal. However, the intervals of time can be selected as desired. For example, the first and third intervals of time during which the pressure is changing in the sacs can be selected to be equal and very short. The second and fourth intervals of time during which the two groups of alternating sacs are maintained at different pressure profiles can also be selected to be equal and can be longer periods of time than the first and third intervals. It also is possible to choose long periods of time for the first and third intervals and short periods of time for the second and fourth intervals.
The foregoing discussion of the pulsation mode according to the present invention is but an example of how pulsation may be achieved and is not intended to limit the invention. For example, pulsation may be achieved so that pressure in the alternating sacs never falls below the first pressure profile of the sacs.
The foregoing discussion of the multi-modal bed employing multi-chambered inflatable sacs is of a preferred system with which the vibratory therapy system may be included. However, it should be appreciated that the vibratory patient support system of the present invention may be utilized in a far less complex supporting structure. For instance, the inflatable cells or other vibratory means may be used with a single chamber air sac on a support structure having only a static or constant pressure mode of operation. Likewise, the bed need not be articulatable. The vibrating means need not operate over the entire patient support surface but, preferably, just over the chest area of the surface.
The accompanying drawings which are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and, together with the description, serve to explain the principles of the invention.